How to connect nodes very fast using shortcut?
Ctrl+Shift+Left-Click on the node and it will connect to the viewer node. If no viewer exists, it will create one.

You can also select two different nodes and press F to connect them automatically (they will try and connect from the first output to the first input if they are available).

The Shift+Left-Click (or right-click as you mentioned) on the node socket output allows you to select which specific node sockets are connected when using F. This means you can also Shift+Left-Click on the target node socket to select which input it will connect to (by default it will connect to the next free input on the node).